Gas-producing compositions, which are used in safety devices for motor vehicles, generally consist of a fuel based on sodium azide and an oxidizing agent. Because of the toxicity of sodium azide, however, attempts have been made since the very beginning to find alternatives to the azide-containing gas-producing mixtures.
U.S. Pat. No. 5,608,183 describes a gas-producing mixture which contains between about 30 and 85% by weight of a fuel and between about 15 and about 70% by weight of an oxidizing agent. At least 60% by weight of the fuel consists of the nitrate of an acid polyamine or a C.sub.2 -C.sub.3 -alkyl diamine, such as for example the nitrates of urea, guanidine, aminoguanidine, diaminoguanidine, semicarbazide, ethylene diamine, propane-1,3-diamine, or propane-1,2-diamine or mixtures thereof. The oxidizing agent comprises at least 60% by weight of basic copper nitrate and/or cobalt triamine trinitrate. The processing of the mixture takes place in a wet process.
The gas-producing mixture known from U.S. Pat. No. 5,608,183, however, has an insufficient ignition ability as well as too low a combustion rate. In addition, since the combustion temperature of the mixture is above 1700 K, an increased portion of toxic gases can be detected in the gas mixture released. Processing the mixture in a wet process requires additional drying stages and is therefore costly.
Thus, there is a continued need for an improved azide-free gas-producing composition for use in safety devices for motor vehicles.